About a week ago, when there was still some question about whether Donald Trump would launch a military offensive in Iran, The New York Times reported, “President Trump said Friday he might use them in a limited strike to pressure Iran to end its nuclear program. Trump badly wants that deal, which his predecessors chased — and never realized.”

Strictly speaking, that wasn’t quite right. One of the Republican’s recent predecessors, Barack Obama, also chased an agreement with Iran over its nuclear program, and unlike Trump (the self-professed world-class dealmaker), the Democrat actually succeeded.

Indeed, that historic breakthrough — to my mind, the greatest feat of international diplomacy since the end of the Cold War — is relevant anew given the ongoing military offensive in Iran.

It wasn’t one of the centerpiece issues of the 2024 presidential race, but then-candidate Trump spent much of the 2024 election cycle claiming he’d nearly completed a nuclear agreement with Iran but ran out of time before leaving the White House in early 2021. Those claims were difficult to believe, but just as notably, they overlooked a key detail: Iran had already reached a nuclear agreement with the U.S. It was called the Joint Comprehensive Plan of Action; it was one of Obama’s most impressive foreign policy accomplishments; and it came to be known as the Iran nuclear deal.

The international agreement with Iran did exactly what it set out to do: The policy dramatically curtailed Tehran’s nuclear ambitions and established a rigorous system of monitoring and verification. Once the policy took effect, each of the parties agreed that the participants were holding up their end of the bargain, and Iran’s nuclear program was, at the time, on indefinite hold.

And then Trump took office and abandoned the policy for reasons he never explained.

In broad strokes, Obama set out to use economic sanctions to get Iran to the international negotiating table. That worked, and a breakthrough agreement eventually followed. Trump came to believe he could duplicate the strategy by abandoning the policy, restoring the old sanctions and adding new ones.

This was known as the Republican’s “maximum pressure” campaign, and it was pursued on the assumption that Iran would inevitably return to the negotiating table and accept a new agreement. If Obama’s sanctions led to a landmark deal, the argument went, then maybe Trump’s sanctions could produce an even better deal.

That didn’t happen. Trump’s approach failed.

In fact, once the U.S. was no longer a part of the agreement, the West lost verification access to Tehran’s program. It was at that point that Iran, rather than begging the White House for attention, almost immediately became more dangerous by starting up advanced centrifuges and ending its commitment to limit enrichment of uranium.

A few years ago, Robert Malley, the then-U.S. special envoy for Iran, told the Senate Foreign Relations Committee that after Trump’s decision, Iranian attacks on U.S. personnel in the region got worse, Iranian support for regional proxies got worse, and the pace of the Iranians’ nuclear research program got “much worse.”

How Trump arrived at his decision adds insult to injury. One of my favorite stories about the Iran deal came a few months into Trump’s term in the White House, when the president held a lengthy meeting with top members of his team: Secretary of State Rex Tillerson, Defense Secretary James Mattis, White House national security adviser H.R. McMaster and Chairman of the Joint Chiefs of Staff Gen. Joseph Dunford. Each of the officials reportedly told Trump the same thing: It was in the United States’ interest to preserve the JCPOA policy.

The Republican expected his team to tell him how to get out of the international agreement, not how to stick with it. When his own foreign policy and national security advisers told him the policy was working, Trump reportedly “had a bit of a meltdown.”

Soon after, he abandoned the JCPOA anyway — not because it was failing, but because Trump was indifferent to its success.

All Trump had to do was nothing. He could have simply left the policy alone and allowed it to keep working. He instead did the opposite. The Republican was convinced his strategy would work — he even boasted at one point during his term that he was prepared to be Iran’s “best friend” — but the entire gambit backfired.

Nearly a decade after abandoning a policy that was working, Trump launched a war in Iran, at least in part because of its nuclear program, which was a problem he made worse.

This post updates our related earlier coverage.